- A. physical change
- B. chemical change
- C. endothermic change
- D. exothermic change
(a) physical change
- A. Condensation and melting
- B. Condensation and freezing
- C. Evaporation and melting
- D. Evaporation and freezing
(a) Condensation and melting
- A. water to clouds
- B. growth of tree
- C. cow dung to bio-gas
- D. ice-cream to molten ice-cream
(c) cow dung to bio-gas
- A. Earthquake
- B. Formation of rainbow in sky
- C. Occurrence of tides in seas
- D. Showering of rain
(a) Earthquake
- A. Dissolution of ammonia in water
- B. Dissolution of carbon-dioxide in water
- C. Dissolution of oxygen in water
- D. Melting of polar ice caps
(b) Melting of polar ice-caps
II.Fill in the blanks :
Filling up a balloon with hot air is a _______ change.
Stretching gold coin into a ring is a _______ change.
Opening a gas cylinder knob converts _______ fuel into _______ fuel. This is an example of _______ change.
Spoiling of food is a _______ change.
Respiration is a _______ change.
physical
physical
liquid, gaseous, chemical
chemical
exothermic chemical
False, Cutting of cloth is an example of a physical change.
False, Taking a glass of water and freezing it by placing it in the freezer is a physical change
False, A bean plant collecting sunlight and turning it into bean seeds is an example of chemical and non-periodic change.
False, if the chemical properties of a substance remain unchanged and the appearance or shape of a substance changes it is called a fossil change.
False, Tarnishing of silver is an example of change.
Physical changes
Bending a paper clip.
Pounding silver into thin plate.
Rolling a chapathi dough into thin wire.
Occurrence of a day and night.
Blinking of eyelids.
Occurrence of a thunderstorm.
Rotation of the earth.
Formation of eclipses.
Painting the grill.
A rough piece of wood is sanded and polished resulting in change in texture.
Dosa from the batter.
Chemical changes
Rusting of a iron
Eruption of volcano
Burning of matchstick.
VI Analogy:
Burning.
Physical change.
Non-periodic.
Seasonal changes, motion of hands of a clock.
Burning of magnesium ribbon and burning of a candle.
Reversible.
Irreversible chemical change.
Physical change.
Growing of nail is a periodic change, because it occurs periodically at regular intervals.
Physical change
Endothermic (heat energy is absorbed)
Physical changes:
No new substance is formed
Reversible
Change in physical properties like size, shape, state
Melting of ice, tearing of paper freezing, evaporation vaporization
Chemical changes:
New substance is formed
Irreversible
Change in properties of reactants and products
Burning of paper, photosynthesis, digestion of food, rusting of iron
A change can occurs in a substance by an alteration in the properties such as colour, texture and the state of the substance since there is formation of a new substance.
Evaporation.
Yes, solar eclipse is a periodic change as it occurs after a definite interval of time.
Dissolution of sugar:
When sugar is dissolved in water it disappears. It we taste the solution, the sugar is still present in dissolved form.
If water is evaporated we get back the sugar.
So it is a physical and reversible change.
Burning of sugar:
Fire activates a chemical reaction between sugar and oxygen. The oxygen in the air reacts with the sugar as the chemical bonds broke.
Energy is released in the form of smoke.
So, burning a sugar is a chemical change.
When we eat, our mouth physically break down food into small pieces.
Mechanical digestion occurs in the mouth, stomach and small intestine.
Food is chemically changed in digestion when new, smaller substances are formed.
Moreover, we will never be able to get back the raw material in the same form as it was before.
Digestion of food is a permanent change which is irreversible.
First the ring in the iron blade of spade is heated.
Heating of the blade leads to its expansion and thus the ring gets bigger.
This happens because metals always expand on heating.
The metal blade is then fitted easily into the wooden handle.
After this, cold water is usually poured on the iron blade which leads to the contraction of the expanded iron blade.
The spade can also be left to cool down, undisturbed so that it is firmly fixed, (vu) The blade is attached firmly to the wooden handle of a spade in this process.
X.Higher order Thinking questions :
No, it is not a chemical change. We just separated the skin of the banana and there is no change is its composition..
When hot glass is cooled fast, the glass cools down unevenly and therefore cause the glass to crack because inside contracts while the outside remains expanded. Glass expands when hot and contracts when cold. It’s a physical but irreversible change.
Boiling of water is a physical change:
On boiling, water is converted into steam. If we cover the beaker with a lid, steam condenses back to water. So, boiling, of water is a physical change since only the physical state of water changes.
Boiling of egg is chemical change:
When egg is boiled, chemical nature of the egg changes. The properties of a boiled egg are totally different from the raw egg. Hence, boiling of an egg is a chemical change.
- A. Both A and R are true and R is the correct explanation of A.
- B. Both A and R are true but R is not the correct explanation of A.
- C. A is true but R is false.
- D. A is false but R is true.
(d) A is false but R is true
- A. Both A and R are true and R is the correct explanation of A.
- B. Both A and R are 11 but R is not the correct explanation of A.
- C. A is true but R is false.
- D. A is false but R is true.
(b) Both A and R are true but R is not the correct explanation Of A.’
- A. Both A and R are true and R is the correct explanation of A.
- B. Both A and R are true but R is not the correct explanation of A.
- C. A is true but R is false.
- D. A is false but R is true.
The correct answer is A Both A and R are false]
- A. Both A and R are true and R is the correct explanation of A.
- B. Both A and R are true but R is not the correct explanation of A.
- C. A is true but R is false. .
- D. A is false but R is true.
(a) Both A and R are true and R is the correct explanation of A.
(a)Physical change
(b)Chemical change
(c) Exothermic
- A. What is name of the process that is done to the kettle?
- B. What will happen to the content of the kettle?
- C. What kind of change is occurring on the cold surface of the metal plate?
- D. What can you say about the quality of water that is obtained in the beaker?
(a) Boiling
(b) Water in the kettle gets converted into vapour
(c) Endothermic
(d) Water vapour converted into liquid (condensation)
Wet clothes dry faster when we unfurl (Spread) them because the rate of evaporation depends on the surface area. If the surface area will be more, rate of evaporation will be higher or more.
Magnesium ribbon must be cleaned before burning. So that the layer of magnesium oxide can be removed in order to get the desired chemical reaction.
Magnesium ribbon burns in air with a dazzling flame and forms a white ash, I magnesium gets oxidised to magnesium oxide.
We feel cool.
When water is added to soap powder we feel hot. When water is added to glucose we feel cold.
Intext Questions.
Physical changes:
Chopping wood
Mixing sand and water
Crushing a can
Mixtures of different coloured buttons
Chemical changes:
Rusting of iron
Digestion of food
Boiling egg
Rotting banana
Burning of wood
Yes, it is a chemical change.
Yes.
Photosynthesis is the process through which plants convert light energy into chemical energy. Here is the chemical reaction involved.
As we can see, water and carbon di oxide combine to form glucose and oxygen.
Since new chemical species are formed, photosynthesis is clearly a chemical change.